#pragma once
#include<iostream>
#include<assert.h>
using namespace std;

namespace wjb
{
	template<typename T>
	struct list_node
	{
		list_node<T>* _next;
		list_node<T>* _prev;
		T _val;

		list_node(const T& val = T())
			:_next(nullptr)
			, _prev(nullptr)
			, _val(val)
		{}

	};

	template<typename T,typename Ref,typename Ptr>
	struct list_iterator
	{
		typedef list_node<T> node;
		typedef list_iterator<T, Ref, Ptr> self;
		node* _node;
		list_iterator(node* n)
			:_node(n)
		{}

		self& operator++()
		{
			_node = _node->_next;
			return *this;
		}
		self operator++(int)
		{
			_node = _node->_next;
			return _node->_prev;
		}
		self& operator--()
		{
			_node = _node->_prev;
			return *this;
		}
		self operator--(int)
		{
			_node = _node->_prev;
			return _node->_prev;
		}

		Ref operator*()
		{
			return _node->_val;
		}

		Ptr operator->()
		{
			return &(_node->_val);
		}

		bool operator!=(const self& it)const
		{
			return _node != it._node;
		}

		bool operator==(const self& it)const
		{
			return _node == it._node;
		}


	};

	template<typename T>
	class list
	{
		typedef list_node<T> node;
	public:
		typedef list_iterator<T,T&,T*> iterator;
		typedef list_iterator<T,const T&,const T*> const_iterator;

		list()
		{
			list_init();
		}

		void list_init()
		{
			_head = new node;
			_head->_prev = _head;
			_head->_next = _head;
		}

		~list()
		{
			clear();
			delete _head;
			_head = nullptr;
		}

		list(const list<T>& lt)
		{
			list_init();
			const_iterator it = lt.cbegin();
			while (it != lt.cend())
			{
				push_back(*it);
				++it;
			}
		}

		list<T>& operator=(list<T> lt)
		{
			swap(lt);
			return *this;
		}

		void swap(list<T>& lt)
		{
			std::swap(_head, lt._head);
			std::swap(_size, lt._size);
		}

		void clear()
		{
			iterator it = begin();
			while (it != end())
			{
				it = erase(it);
			}
		}

		void push_back(const T& val = T())
		{
			/*node* tail = _head->_prev;
			node* newnode = new node(val);
			tail->_next = newnode;
			newnode->_prev = tail;
			newnode->_next = _head;
			_head->_prev = newnode;*/
			insert(end(),val);
		}
		void pop_back()
		{
			erase(--end());
		}

		void push_front(const T& val) 
		{ 
			insert(begin(), val); 
		}
		void pop_front() 
		{ 
			erase(begin()); 
		}


		iterator begin()
		{
			return _head->_next;
		}
		iterator end()
		{
			return _head;
		}
		const_iterator cbegin()const
		{
			return _head->_next;
		}
		const_iterator cend()const
		{
			return _head;
		}

		iterator erase(iterator pos)
		{
			assert(pos != end());
			node* ret = pos._node->_next;
			pos._node->_prev->_next = pos._node->_next;
			pos._node->_next->_prev = pos._node->_prev;
			delete pos._node;
			_size--;
			return ret;
		}

		void insert(iterator pos,const T& val = T())
		{
			node* newnode = new node(val);
			node* cur = pos._node;
			node* prev = cur->_prev;
			cur->_prev = newnode;
			prev->_next = newnode;
			newnode->_next = cur;
			newnode->_prev = prev;
			_size++;
		}

		size_t size()const
		{
			return _size;
		}
		bool empty()const
		{
			return _size == 0;
		}
		
	private:
		node* _head;
		size_t _size;
	};


	//test

	void Print(const list<int>& lt)
	{
		list<int>::const_iterator it = lt.cbegin();
		while (it != lt.cend())
		{
			// (*it) += 1;
			cout << *it << " ";
			++it;
		}
		cout << endl;
	}

	void test_list1()
	{
		list<int> lt;
		lt.push_back(1);
		lt.push_back(2);
		lt.push_back(3);
		lt.push_back(4);

		list<int>::iterator it = lt.begin();

		while (it != lt.end())
		{
			(*it) += 1;
			cout << *it << " ";
			++it;
		}
		cout << endl;

		for (auto e : lt)
		{
			cout << e << " ";
		}
		cout << endl;

		Print(lt);
	}

	struct A
	{
		A(int a1 = 0, int a2 = 0)
			:_a1(a1)
			, _a2(a2)
		{}

		int _a1;
		int _a2;
	};

	void test_list2()
	{
		list<A> lt;
		lt.push_back(A(1, 1));
		lt.push_back(A(2, 2));
		lt.push_back(A(3, 3));
		lt.push_back(A(4, 4));

		list<A>::iterator it = lt.begin();
		while (it != lt.end())
		{
			//cout << (*it)._a1 << " " << (*it)._a2 << endl;
			cout << it->_a1 << " " << it->_a2 << endl;

			++it;
		}
		cout << endl;
	}

	void test_list3()
	{
		list<int> lt;
		lt.push_back(1);
		lt.push_back(2);
		lt.push_back(3);
		lt.push_back(4);
		lt.push_front(5);
		lt.push_front(6);
		lt.push_front(7);
		lt.push_front(8);
		for (auto e : lt)
		{
			cout << e << " ";
		}
		cout << endl;

		lt.pop_front();
		lt.pop_back();

		for (auto e : lt)
		{
			cout << e << " ";
		}
		cout << endl;

		lt.clear();
		lt.push_back(10);
		lt.push_back(20);
		lt.push_back(30);
		lt.push_back(40);
		for (auto e : lt)
		{
			cout << e << " ";
		}
		cout << endl;

		cout << lt.size() << endl;
	}

	void test_list4()
	{
		list<int> lt;
		lt.push_back(1);
		lt.push_back(2);
		lt.push_back(3);
		lt.push_back(4);

		for (auto e : lt)
		{
			cout << e << " ";
		}
		cout << endl;

		list<int> lt1(lt);
		for (auto e : lt1)
		{
			cout << e << " ";
		}
		cout << endl;

		list<int> lt2;
		lt2.push_back(10);
		lt2.push_back(20);
		lt2.push_back(30);
		lt2.push_back(40);

		for (auto e : lt2)
		{
			cout << e << " ";
		}
		cout << endl;

		lt1 = lt2;

		for (auto e : lt1)
		{
			cout << e << " ";
		}
		cout << endl;
	}
}